Re: Radial tires

["P. O. Johnson" <pojhome@FLASH.NET>]

I went to Michelin's home page, and thence to
http://www.michelin.com/us/eng/tire/guide/lesson2.html, to see what they had
to say about tire nomenclature. Not much.

I agree with Chuck that the term bias-ply derives from sewing. In both
sewing and in tires, the term refers to a direction at 45 degrees to the
principle direction. I also suspect that Michelin coined the name "radial"
for their new tire design because each cord lies in a radial plane. Is not
this plane radial to both axes of the toroid, the straight center axis that
the tire spins around and the circular axis that runs along the center of
the toroid? I'm not enough of a mathematician to know (or want to know) the
official names of these two axes.

poj
Collin County College

----- Original Message -----
From: "Chuck Britton" <britton@ACADEMIC.NCSSM.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Sunday, December 19, 1999 3:50 PM
Subject: Radial tires


> John S. Denker" <jsd@MONMOUTH.COM> wrote:
>
> I'm never sure what such things mean, either.  There's too much
> inconsistent usage.  The one that really cracks me up is radial tires.
> The key patented component runs in a direction that I cannot bring myself
> to call radial.  See
>    http://www.michelin.com/us/eng/groupe/images/ph113g-a.jpg
> ~~~~~~~~~~~~~~~~~
>
> I checked out the jpeg and DO see your confusion! That picture indeed
fails
> to show the 'radial' aspect of the tire construction.
>
> Can you understand why the 'conventional' construction on the left is
often
> called 'bias' ply?
> Folks who sew know that cutting on the bias implies a 45 degree angle to
> the threads (cords) of the fabric. The bias ply tires were quite strong
> because of this alternating cord direction, much like the alternating
grain
> direction in 'ply' wood. Unfortunately, this rigid sidewall construction
> also led to lots of internal friction as the portion of tire in contact
> with the road had to squish down. As the plys flexed, they had to rub
> against each other, not only creating excess ' thermal energy' but adding
> to the rolling resistance of the tire.
>
> What the Right Hand jpeg clipping does NOT show is the cords of the
'radial
> ply' tire running directly from the tread (belts) and the 'bead' (where
the
> tire meets the rim).
> These cords run 'parallel' to each other and could conceivable be
> visualized as being in the radial direction since each is directed toward
> the hub of the wheel. This cord arrangement yeilds considerably less
> internal friction and a more flexible sidewall for the tire.
>
> The clipping in question seems to be illustrating the 'tangential' steel
> belts that allowed Michelin to successfully introduce the radical, radial
> construction.
>
> When was the last time anybody bought bias ply tires instead of steel
> belted radials?
>
> It's no accident that stressed          Chuck Britton
> spelled backwards is desserts.          britton@odie.ncssm.edu